1. Field of the Invention
The present invention relates generally to spring loaded solenoid and the like devices that might be overcome by external forces, and in more specific embodiments to electronic locks having spring loaded solenoids and the like that might be overcome by external forces.
This invention also relates generally to electronic security systems, and more particularly to electronic security systems for money-containing devices in telephone chassis, vending machines, parking meters and the like which must be periodically accessed by a collector in order to retrieve the funds accumulated in the device.
2. Description of the Background Art
Typically, in devices having electronically activated solenoids which contain a spring biased element, such as a pin, that is moved when the solenoid is energized, the spring biased element can potentially be moved by subjecting the solenoid to rapid acceleration or external forces. As a result, the spring biased element can potentially be moved relative to the solenoid housing and, thus, create a temporary situation similar to having the solenoid in an "activated" condition.
In electronic locks having a solenoid member that is used to allow access only upon an appropriate electronic determination that access is appropriate, there remains the possibility that an individual can tamper with the lock in a manner to cause the solenoid element to move relative to the solenoid housing and create a condition under which the solenoid is temporarily in an activated condition.
For example, vending machine locks, telephone chassis locks, parking meter locks and locks in other devices can be subjected to forces--such as striking via a hammer--that can cause a rapid acceleration sufficient to cause the solenoid to move relative to the solenoid element, or solenoid pin. Electrically locked enclosures that are mounted in a manner that can allow movement of the enclosure, and the lock itself, are susceptible to tampering. For example, a less rigidly mounted telephone chassis could potentially be moved to enable tampering with the device. Electrically locked enclosures that are non-fixed, free hanging or pole mounted, etc., can be particularly susceptible to such tampering. For example, electronic parking meter locks are susceptible to tampering because electronic parking meter locks are typically contained within relatively small metal housings located upon metal poles. As a result, these housings are relatively easily accessed, handled and/or tampered with.
The collection of money from coin or currency operated devices such as telephone chassis, parking meters and the like is a costly and burdensome operation. For instance, a company may own tens or even hundreds of thousands of locked enclosures for which tens or hundreds of keys must be kept in order to prevent the loss of a key from requiring the changing of locks on thousands of devices which would operate with the lost key. Accordingly, it is particularly desirable to establish a system under which these locked enclosures can be "electronically" accessed and monitored, while maintaining high theft-deterrence to avoid large scale problems that could otherwise be difficult to handle due to the large numbers and various locations of such devices.
A significant problem involved with the collection of funds from currency operated devices is the possibility of fraud or theft by the collector himself. Typically, a collector should remove a full and locked coin box from the device and replace it with an empty coin box to which he does not have access. However, it is possible that a removed coin box will not be replaced with another lock box but rather will be replaced with an unsecured receptacle which can be later removed by that collector before turning in his key at the end of the collection shift. Yet another cost involved in the collection process is the sheer manpower required for the task of distributing, collecting, and keeping track of many keys on a daily basis. Therefore, it is highly desirable to have an electronically controlled access; however, it is also critical to employ means that ensure that such electronic control cannot be overcome by tampering.
Although electronic security systems are known and have been used for various purposes, see e.g. U.S. Pat. Nos. 4,789,859, 4,738,334, 4,697,171, 4,438,426, the existing art does not adequately address the problems noted above. There still remains a need for an improved anti-tampering device for electronic solenoids having spring-biased elements, such as used in electronic locks for vending machines, telephones, parking meters and the like.